Drive trains of this type are preferably used in working machines such as wheel loaders or graders, in which a drive engine, preferably a diesel engine, is connected to the pump impeller of a hydrodynamic converter whose turbine shaft forms the drive input for a shiftable transmission which is connected to drive wheels. An auxiliary drive for powering at least one hydraulic pump, in particular for the working hydraulic system of the working machine, is also connected to the drive engine and is preferably connected to the drive shaft of the hydrodynamic converter. The drive engine and the hydrodynamic converter are designed so that at the fixed braking point, i.e., when the vehicle is stationary under full load and the working hydraulic system is not actuated, the diesel engine runs at a nominal speed. This is necessary so that, at the fixed braking point, the working hydraulic system can be actuated without reducing the speed of the diesel engine below a necessary minimum speed and so stalling it. In most driving conditions, however, the diesel engine is oversized, which has an adverse effect on the manufacturing cost of the vehicle.
DE 195 21 458 A1 discloses an electro-hydraulic control device for the drive of a machine in which, between the diesel engine and the hydrodynamic converter, a clutch is arranged which can always be actuated in the opening direction when the driving speed of the vehicle is low, but sufficient volume flow has to be provided for the working hydraulic system.
The purpose of the present invention is to provide a drive train for powering a mobile vehicle, in particular a working machine, in which a less expensive drive engine can be used, but sufficient volume flow will be available for the working hydraulic system.
This objective is achieved with a drive train of the type described for powering a mobile vehicle.